Fabrication And Biocompatibility Of Electrically Conducting Polymer-Polypyrrole-Hyaluronic Acid Composite Biomaterials For Biological Applications

Object New tissue engineering technologies will rely on biomaterials that physically support tissue growth and stimulate specific cell functions. The goal of this study was to create a biomaterial that combines inherent biological properties which can specifically trigger desired cellular responses (e.g., angiogenesis) with electrical properties which have been shown to improve the regeneration of several tissues (e.g., nerve) .Materials and methods In this paper, the electrically conductive polymer—oxidized polypyrrole (PPy)—has been evaluated for use as a substrate to enhance nerve cell interactions in culture as a first step toward potentially using such polymers to stimulate in vivo nerve regeneration. To this end, composites of the biologically active polysaccharide hyaluronic acid (HA) and the electrically conducting polymer polypyrrole (PPy) were synthesized and characterized. Electrical conductivity of the composite biomaterial (PPy/HA) was measured by a four-point probe technique, scanning electron microscopy was used to characterize surface topography, FTIR were used to evaluate surface and bulk chemistry. PPy/HA materials were also evaluated for in vitro cell compatibility and tissue response in rats.Results Image analysis demonstrates that PC-12 cells attached and extended neurites equally well on both PP films and tissue culture polystyrene in the absence of electrical stimulation. However, PC-12 cells cultured on PPy films and subjected to an electrical stimulus through the film showed a significant increase in neurite lengths compared with ones that were not subjected to electrical stimulation through the film and tissue culture polystyrene controls. The median neurite length for PC-12 cells grown on PP and subjected to an electrical stimulus was 38.60 (n= 1748) compared with 26.16 (n=2251) for NS, 23.60 (n=1699) for SC, and 24.68 (n=l 143) for TCPS. Furthermore, animal implantation studies reveal that PPy invokes little adverse tissue response compared with poly (lactic acid-coglycolic acid). Smooth, conductive, HA-containing PP films were produced; these films retained HA on their surfaces for several days in vitro and promoted vascularization in vivo. The median neurite length in the 'S' cases [44.05 for bilayer PPy/HA and 38.6 for PPy/PSS] is about 1.5 times to twice that of the controls [25.45 for NS-bilayer PPy/HA, 26.16 for NS-PPy/PSS, 19.33 for SC-bilayer PPy/HA, 23.595 for SC-PPy/PSS, and 24.68 for TCPS] confirms that the neurite distribution in the "S" case reveals a significant increase in the neurite lengths.Conclusion The study showed that PPy is a suitable material for in vitro nerve cell culture and that application of an electric stimulus through PPy enhances neurite outgrowth. In addition, PP did not elicit an adverse tissue response when implanted in rats. PPy/HA composite biomaterials are promising candidates for tissue engineering and wound-healing applications that may benefit from bothelectrical stimulation and enhanced vascularization.